<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
    *{
        margin: 0;
        padding: 0;
    }
    .tou{
        width: 450px;
        height: 50px;
        background-color: rgba(137, 43, 226, 0.253);
        margin: 0 auto;
    }
    /* 一级导航背景 */
    .tou li{
        width: 150px;
        float: left;
        list-style: none;
        text-align: center;
        line-height: 50px;
    }
    /* 一级导航字体的调试 */
    .tou_1{
        width: 300px;
        height: 150px;
        background-color: burlywood;
        display: none;
    }
    /* 二级导航 */
    .tou li:hover .tou_1{
        display: block;
        text-decoration: overline;
    }
    /* 点击一级导航触发的二级导航 */
    .tou li:hover .tou_2{
        display: block;
        text-decoration: overline;
    }
    /* 点击一级导航触发的二级导航 */
    .tou li:hover .tou_3{
        display: block;
        text-decoration: overline;
    }
    /* 点击一级导航触发的二级导航 */
    .tou_2{
        width: 300px;
        height: 150px;
        background-color: darkorchid;
        display: none;
    }
    /* 二级导航 */
    .tou_3{
        width: 300px;
        height: 150px;
        background-color: lightgreen;
        display: none;
    }
    /* 二级导航 */
    </style>
</head>
<body>
    <ul class="tou"> 
        <li>财经
        <div class="tou_1"></div></li>
        <li>股票
        <div class="tou_2"></div></li>
        
        <li>理财
        <div class="tou_3"></div></li>
        
    </ul>
</body>
</html>